Just replace the batteries annually. I didn't - never flattened a set of D cells in the 2 & 3 D cell Maglites with the LED conversion. I did get to toss out two pretty ones, a 2 & a 3 cell one, when the cells leaked all inside. Their cells were two years old, or less - one set of Ray-o-vacs and one of Duracell. The low current demand lulls you into a false security - they still digest their cases with age. I still have a few - their cells are in ZipLoc bags with them... under my bed. I keep CR123 Lithium battery users, mostly Surefire but also an Olight or two and a Fenix, 'loaded' and at the ready. They are smaller and brighter - and those cells last for 10-11 years shelf life. I've never had one explode, either. If you use them up quickly, C-Zn/alkaline celled flashlights are okay - at least the cells are still widely available. BTW, always buy Surefire CR123's - they are US-made and $2/each or less in 12 piece boxes.
Stainz